Ring binder mechanism having a convex central rib



FIG. 1 is a perspective view of the ring binder mechanism having a convex central rib showing of my design;

FIG. 2 is a front elevation view of the ring binder mechanism having a convex central rib, the rear elevation view being a mirror image thereof;

FIG. 3 is a top plan view of the ring binder mechanism having a convex central rib thereof;

FIG. 4 is a bottom plan of the ring binder mechanism having a convex central rib thereof;

FIG. 5 is a right side elevation view of the ring binder mechanism having a convex central rib, the left side elevation view being a mirror image thereof; and,

FIG. 6 is a cross-section view of the ring binder mechanism having a convex central rib, taken along line 6-6 in FIG. 3.

The broken lines in the drawings illustrate portions of the ring binder mechanism having a convex central rib and form no part of the claimed design. 

CLAIM The ornamental design for a ring binder mechanism having a convex central rib, as shown and described. 